First Love
by Aster Verzen
Summary: Ishigami Senkuu's first love, was not science.


**First Love.**

**-'-**

**A/N:** 'so, shiver by fiveamradio'. That is the inspiration for the following story, you may find it in AO3. I recommend you check that fic out.

Whereas 'so, shiver' is technically a SenGen, this is the rare SenkuuxByakuya BL nobody asked for. Don't like the idea, don't read it. It will get explicit.

**-'-**

**One.**

Ishigami Senkuu's first love, was not science.

His father did whatever he could to impress his little boy, going as far as to sell his own car to get equipment for Senkuu's thirst for knowledge. But Byakuya didn't need to impress the kid. Senkuu loved him just by being there for him. But time passes, bodies, minds, and so many other things grow; _change_. Senkuu's love for Byakuya underwent a similar process. It remained love, nonetheless.

When he hit puberty –he must've been a twelve year old– the nights became short –_restless_–. Dreams filled with warm big hands –bigger than his own– touching ever so firmly –ever so un-innocently– everywhere on the boy's skin, anywhere on the boy's body, leaving him begging –_please!_–, whispering –_yes!_–, moaning –_more!_– an absolute disaster engulfed in a strange –familiar– warmth. He dreamt of a raspy known voice sighing sweet words in his ear. And the sun revealed a sweaty –_sticky_– tangled mess in the bed, a flushed barely teen who realized a troublesome truth.

**-'-**

**Two.**

Ishigami Byakuya loves his son more than anything or anyone in the world. Even if the boy was a _cocky-want-to-know-it-all-**little-shit**_ who dismissed most things that weren't science related; the man knew he was kind hearted. And even if Senkuu hadn't been, he still would've done anything for him.

He loves to see the smile on his son's face. Wonders why such a tiny kid speaks with so much sobriety, refusing most things kids his age seek. His exasperating personality is almost endearing.

The boy likes Doraemon, likes to dismantle the electric appliances beyond repair until he could understand it's internal workings, the boy causes little and big explosions inside and outside the house. He caught him trying on his shoes several sizes too big for him. He wants candy and ramen and Doraemon and science and the stars and to hold his hand –the man has noticed–, and to know why the moon follows him so intently. And Byakuya can't, by the life of him, deny Senkuu anything he wants. He spoils him _rot_.

**-'-**

**Three.**

Ishigami Senkuu likes the warmth in his father's hand. He likes it when he pats his head and praises him. Whenever Byakuya calls him: '_cute_', Senkuu gets warm everywhere. When Byakuya refers to him as: '_my boy_', Senkuu is happy. Sometimes too, Byakuya will call him: '_my little genius_', and he likes to hear his father's voice spilling such words.

In the mornings, when they're both barely just awake and Byakuya makes breakfast with slow lethargic movements, Senkuu can only stare –at his back, at his hands, _at him_– with his big red eyes and notice how out of place his father's hair is, the slight crumple in his shirt, the looseness in his pants, the persistent tug of sleep in his gaze, the unshaved stubble in his chin –which he knows tickles–. He watches every last detail of his father's figure.

Some nights –some highly infrequent nights– when sleep would not come for unknown reasons and he couldn't imprison sleep within his eyelids, he'd snuck up into Byakuya's bed, snuggle beneath the blankets and nuzzle in his neck –feeling the itchy stubble– trying to pass Byakuya's tranquil breathing –light snoring– as a lullaby. And he woke in the man's arms, with a kiss to his forehead and a groggy smile.

**-'-**

**Four.**

Senkuu is no longer a child. He's a teenager. Collected and cold headed. A scientist. A kid trapped between boy and man. A teen with his hormones trying to break havoc in his daily life. It'd be fine, if he had the hots for some cute girl. It'd be okay, if he daydreamed about a handsome boy. Instead he wants his father's voice a low rumble on his ear. Instead he wants his father to roam his hands through his gravity defying hair, pushing a leg between his, and then... **_Stop_**.

Senkuu's cheeks heat up, he cuts himself with these illogical thoughts. Byakuya is his father and nothing more. He loves him dearly, as the man who raised him, and that is all he should ever feel.

''Senkuu! Wanna watch the stars with me? The sky is so clear tonight!'' beams the offending man with an ear splitting goofy grin.

Byakuya doesn't seem to make things easier for him, though.

**-'-**

**Five.**

One night –one highly infrequent night– he decides to sneak on his father's bed, only to find him staring at his phone screen.

"Senkuu?" he questions, an eyebrow raised.

"Can't sleep" mumbles Senkuu as he gets underneath the covers.

The man smiles as he pulls him close, holding the boy with one arm. Senkuu lays his head on the crook of Byakuya's neck, the open palm of his hand on the steady heartbeat of the eldest's chest. His father resumes whatever it is that he's watching on his phone, as the teen feels the pulse, rythmic, calm, and counts the beats. _One, two, three, four._ Byakuya chuckles, lightly. _Five_. Senkuu can feel the vibration echoing on his body. _Six, seven, eight._ The boy lets out a breath, right on Byakuya's neck, so the man shivers. _Nine, ten._ Senkuu turns the other way, giving his back to Byakuya.

"What's wrong, Senkuu?"

He stays silent, and can hear the phone being placed on the nightstand, his father's right hand falling in front of his chest, the left caresses his unusual mop of hair. Trapped between his father and the bed, Senkuu finds himself with a dilemma.

"You know, I've noticed you've been acting strange lately..." the man whispers.

Senkuu shrinks in on himself.

"You can tell me if anything happened, you know" he assures him.

But the boy cannot voice his true thoughts.

"I'm okay" he lies.

"Senkuu. You can't lie to save your life"

He shrinks even more. Byakuya sighs, and plops on his back, placing both arms beneath his head. They stay silent. Worry, for the man, guilt for the teen.

"I have a crush" he finally relents.

"Eh?"

The man bursts with laughter.

"So cupid has finally hit you with his arrow!" he exclaims patting Senkuu's back approvingly. "Who's the lucky lady?"

"It's not a girl" he mumbles.

"A boy then! Who?"

"I can't tell you"

Once more, there is silence.

"Is it Taiju?" he asks cautiously.

"No"

"Is it someone I don't know?"

He gets no answer, and Senkuu buries his face on the pillow.

"No" comes the muffled answer.

Byakuya scratches his chin, pensative. He goes through a list in his head, trying to remember names and faces looking for the person his son might have a crush on. He comes out blank. If Taiju is not the right answer, then who is?

"It's you" Senkuu's voice is a mere broken sob, muffled into the fabric of the pillow he's hiding with.

Byakuya does not know what to say.

**-'-**

**Six.**

It's awkward at first, but Senkuu acts as if nothing had transpired the night before, so Byakuya lets it be for now. They wake up, and he cooks breakfast aware of the crimson gaze poking holes through his back, attentive to his every move.

He thinks of it, on his free time, he goes back to the shrinking lad in his bed trying to merge into a pillow. It must've been hard on him, admitting such a thing. It was normal he supposed, for a kid to develop a crush on their parents, actually, now that he thought about it, it was an unusually normal behavior for his son. Still, there was the issue of what to do, he couldn't act like it hadn't happened, denying the fact wouldn't do any good for Senkuu. But then again, would responding to his feelings be the right thing to do?

**-'-**

**Seven.**

"Alright. I think we need to talk" says Byakuya.

It's saturday morning, when they eat their lunch. Senkuu stops his chopsticks midway to his lips, pausing to look at his father.

"Talk about what?" he already has a hunch as to what it is.

"What you said to me the other night" Byakuya scratches his neck. "About having a crush on me"

"Ah. Yes. That. A sort of Edipo's complex. Don't worry about it. Kids get crushes on their parents all the time. Actually forget it. Is nothing. It will go away. Actually you could say it's already leaving" his words come rushed out in one breath, avoiding Byakuya's eyes.

"Senkuu" his father tuts him. "You truly can't tell a lie to save your life"

Senkuu's ears are tinted pink, his whole face seems to be a ripe tomato, it seems like tears prickle at the corner of his eyes, but his face is cast down, so Byakuya can't be sure.

"We can forget about it" whispers Senkuu.

"Can you really forget it?"

The boy's head lowers a bit more, his bangs obscure his eyes.

**-'-**

**Eight.**

The next thursday when Senkuu arrives home early, Byakuya has the day off; but the boy already knew this. He finds his father sitting on the couch, with a laptop balancing on his legs, he's pressing the keys, typing what seems to be a correction to a test.

"Welcome home"

Byakuya gets no answer, knowing Senkuu is right behind him, he turns to look at him. The boy drops his backpack on the floor and moves slowly to remove the laptop from his grasp to cast it aside. The man's eyes follow his movements. He sits on his father's lap, facing him as he cups his cheeks with his hands.

"I love you, dad. I love you a lot" Is all Senkuu says. Byakuya places his hands on his son's thighs, and squeezes them.

"I love you too, Senkuu" There is nothing else he could've answered.

And he didn't need to say much more. Senkuu placed a chaste kiss on his lips.

**-'-**

**Nine.**

Is a chilly night, the wind howls enraged as if it wanted to rip even the tallest of buildings like a leaf. The wind tunes out Senkuu's feeble moans, as Byakuya's lips leave a trail of kisses from his chin down his neck, and onto his chest.

"Ah! Byaku-!"

A mouth closes on one of his nipples, sucking and biting lightly, his fingers going to tease the other one. Senkuu squirms, his legs draped securely over Byakuya's waist trapping him in place. His mouth goes back to the teen's neck leaving small hickeys, that would fade just enough to hide in the morning. Senkuu grabs his face and kisses him once, twice –all tongue and teeth and _need_– inexpertedly with desire. The man takes the lead, trying to calm down the youngest of the two with tender caresses, slowing down their pace. The teen defies him, grinding his hips against Byakuya's as he keeps his gaze steady on him.

"_Behave_" reprimands the eldest.

And it is so rare, to hear such an imposing word from his lips that the teen complies with no further fuss, he melts into his father's arms, moaning low.

"_Daddy_" he whimpers.

And it is so rare, to hear such a word spill from his boy's tongue that the man kisses him deeply once again, until their lips bruise and their breath is scarce and the blush on the boy's cheeks spreads to his own face. He takes the arms clutching his neck, and leaves them above the teen's head to better take off his shirt. He removes Senkuu's legs from his hips, and tugs at the elastic band at the waist of his pants.

"Senkuu. If we do this, there will be no turning back" he warns.

"I know" He tugs on his father's shirt. "_Please_. I want you, daddy"

Byakuya pulls his pants and underwear down in one swift motion, leaving Senkuu completely bare before him. He's hard, that's the first thing he notices, so he places a kiss on Senkuu's beating heart as he slides his hand gently down until he grabs his member, making Senkuu groan and buck his hips forward. His pace is slow –he's still unsure himself–, trying his best to be gentle. Senkuu's hand ventures down to the bulge in Byakuya's pants, getting inside the fabric, touching Byakuya's barely awake length, pumping him until he's as hard as him, causing the eldest to pick up his pace. They soon reach their peak. And the room is filled with quick breaths –wet sounds–, the scent of sweat and sex stains the sheets.

"Faster!" Senkuu begs.

Byakuya complies, as he does with everything the kid wants. And they both come. The man buries his face on Senkuu's neck, the boy's free hand cups the nape of his neck, pressing his lips to Byakuya's ear.

"Again" he whispers.

**-'-**

**Ten.**

He wakes up, in his father's arms –basked in his warmth, his scent,_ in him_– feeling nothing but bliss.

Ishigami Byakuya, is unable to deny anything his boy wants. He spoils him _rot_. And Ishigami Senkuu's first love, was not science.

**-'-**


End file.
